CVE-2025-40153
Description
In the Linux kernel, the following vulnerability has been resolved:
mm: hugetlb: avoid soft lockup when mprotect to large memory area
When calling mprotect() to a large hugetlb memory area in our customer's workload (~300GB hugetlb memory), soft lockup was observed:
watchdog: BUG: soft lockup - CPU#98 stuck for 23s! [t2_new_sysv:126916]
CPU: 98 PID: 126916 Comm: t2_new_sysv Kdump: loaded Not tainted 6.17-rc7 Hardware name: GIGACOMPUTING R2A3-T40-AAV1/Jefferson CIO, BIOS 5.4.4.1 07/15/2025 pstate: 20400009 (nzCv daif +PAN -UAO -TCO -DIT -SSBS BTYPE=--) pc : mte_clear_page_tags+0x14/0x24 lr : mte_sync_tags+0x1c0/0x240 sp : ffff80003150bb80 x29: ffff80003150bb80 x28: ffff00739e9705a8 x27: 0000ffd2d6a00000 x26: 0000ff8e4bc00000 x25: 00e80046cde00f45 x24: 0000000000022458 x23: 0000000000000000 x22: 0000000000000004 x21: 000000011b380000 x20: ffff000000000000 x19: 000000011b379f40 x18: 0000000000000000 x17: 0000000000000000 x16: 0000000000000000 x15: 0000000000000000 x14: 0000000000000000 x13: 0000000000000000 x12: 0000000000000000 x11: 0000000000000000 x10: 0000000000000000 x9 : ffffc875e0aa5e2c x8 : 0000000000000000 x7 : 0000000000000000 x6 : 0000000000000000 x5 : fffffc01ce7a5c00 x4 : 00000000046cde00 x3 : fffffc0000000000 x2 : 0000000000000004 x1 : 0000000000000040 x0 : ffff0046cde7c000
Call trace: mte_clear_page_tags+0x14/0x24 set_huge_pte_at+0x25c/0x280 hugetlb_change_protection+0x220/0x430 change_protection+0x5c/0x8c mprotect_fixup+0x10c/0x294 do_mprotect_pkey.constprop.0+0x2e0/0x3d4 __arm64_sys_mprotect+0x24/0x44 invoke_syscall+0x50/0x160 el0_svc_common+0x48/0x144 do_el0_svc+0x30/0xe0 el0_svc+0x30/0xf0 el0t_64_sync_handler+0xc4/0x148 el0t_64_sync+0x1a4/0x1a8
Soft lockup is not triggered with THP or base page because there is cond_resched() called for each PMD size.
Although the soft lockup was triggered by MTE, it should be not MTE specific. The other processing which takes long time in the loop may trigger soft lockup too.
So add cond_resched() for hugetlb to avoid soft lockup.
AI Insight
LLM-synthesized narrative grounded in this CVE's description and references.
A missing cond_resched() in the Linux kernel's hugetlb_change_protection() can cause soft lockups when mprotect() is called on large hugetlb memory areas.
Vulnerability
Description
In the Linux kernel, the function hugetlb_change_protection() iterates over a range of huge pages without a rescheduling point. When mprotect() is called on a large hugetlb memory area (e.g., ~300 GB), this loop can monopolize a CPU for tens of seconds, triggering a soft lockup. The issue is not specific to Memory Tagging Extension (MTE), although the reported stack trace shows mte_clear_page_tags() as the long-running operation; any per-page processing in the loop could cause the same problem. [1]
Exploitation and
Attack Surface
An attacker with the ability to invoke mprotect() on a large hugetlb mapping (which requires local access and appropriate permissions) can trigger a soft lockup, leading to a denial of service (DoS) condition on the affected CPU. No special privileges beyond the ability to call mprotect() on a hugetlb region are needed. The attack surface is limited to systems where hugetlb pages are configured and accessible to the attacker. [1]
Impact
A successful exploitation results in a soft lockup, causing the CPU to become unresponsive for an extended period (23 seconds in the reported case). This can degrade system performance or cause a complete denial of service for processes relying on that CPU. The vulnerability does not lead to privilege escalation or data corruption. [1]
Mitigation
The fix adds a cond_resched() call inside the loop in hugetlb_change_protection(), allowing the kernel to yield the CPU and prevent soft lockups. The patch has been applied to the stable kernel trees as commits 547e123e9d34, 30498c44c2a0, and f52ce0ea90c8. Users should update to a kernel version containing these commits. [1][2][3]
AI Insight generated on May 19, 2026. Synthesized from this CVE's description and the cited reference URLs; citations are validated against the source bundle.
Affected products
2Patches
830498c44c2a05783485ab2be547e123e9d34957faf9582f9964598e6f70a4975c975ed94c6096f3947f6f52ce0ea90c8Vulnerability mechanics
Generated on May 9, 2026. Inputs: CWE entries + fix-commit diffs from this CVE's patches. Citations validated against bundle.
References
8- git.kernel.org/stable/c/30498c44c2a0b20f6833ed7d8fc3df901507f760nvd
- git.kernel.org/stable/c/4975c975ed9457a77953a26aeef85fdba7cf5498nvd
- git.kernel.org/stable/c/547e123e9d342a44c756446640ed847a8aeec611nvd
- git.kernel.org/stable/c/5783485ab2be06be5312b26c8793526edc09123dnvd
- git.kernel.org/stable/c/957faf9582f92bb2be8ebe4ab6aa1c2bc71d9859nvd
- git.kernel.org/stable/c/964598e6f70a1be9fe675280bf16b4f96b0a6809nvd
- git.kernel.org/stable/c/c6096f3947f68f96defedb8764b3b1ca4cf3469fnvd
- git.kernel.org/stable/c/f52ce0ea90c83a28904c7cc203a70e6434adfecbnvd
News mentions
0No linked articles in our index yet.